Heart rate training zones are used as a guide to maximize the
benefit of your training. Each zone is used for training or developing a specific
physiological response. Low heart rate zones are mainly for developing aerobic energy sources
and pathways; higher zones may develop the anaerobic pathways or the ability for the body to
clear lactic acid.

Using Maximum Heart Rate. If you don't have a handy physiology lab, there are alternatives ways of finding those zones. The easiest
is to use percentage of maximum heart rate. Unfortunately, depending on who's book you read,
the percentages and the number of zones vary. For example, Brian Sharkey ("Training for Cross-Country
Ski Racing") defines four zones, starting at 70% of max heart rate, but Rob Sleamaker and
Ray Browning ("SERIOUS Training for Endurance Athletes") have five zones, starting
at 60% of max heart rate. Let's compare the two methods:

Although the zones and percentages vary, there are
many similarities: Aerobic sources and pathways are improved at lower heart rates; anaerobic
sources and pathways at higher heart rates. We'll talk about the differences in the final
section of this article...

Using VO2
Max. If you have results from a physiology test, you can use more precise methods to
determine training zones. The training zones I've been using since June were determined
from testing on a treadmill during a XC Oregon physiology lab test in June (more information about that
test here). The physiologists used a combination of
VO2, Heart Rate, and Lactic Acid levels to determine my training zones.

Sleamaker and
Browning also use a method that plots heart rate against VO2 utilization to
determine training zones. Essentially, they use the following method to determine training
zones: From a graph that plots VO2 against heart rate, find the heart rates that
match up to the table below to determine training zones:

Sleamaker and Browning Method of
using VO2against Hear Rate to Determine Training Zones

What a mess! Zones and heart rates are all over the place!
Which method is the best to use?

I have several thoughts.

First, the use of a physiology test is very personal and
provides the best results.

Second, a physiology test that uses more variables to
determine zones is better than one that uses fewer variables.

Third, it's generally better to err on the side of going
too easy than going too hard.

Based on these two criteria, I'm using my results from the
XC Oregon physiology test because it takes into account VO2, heart rate, AND lactic
acid levels. Sleamaker & Browning's method based on just VO2 and heart rate
comes fairly close and is my second choice. S&B's Zones 1 & 2 match up almost exactly
with XC Oregon's Zone "2". The main difference is in Zone 4 where S&B could have
me training at too low a heart level. Based on my experience, I can do intervals in the
160-164 heart rate range without getting totally trashed.

How do the different zones translate into percent of max
heart rate for me?

Zone

Heart Rate
Range from
XC Oregon
physiology test

Percent of
Max Heart Rate
(Max = 174 bps)

Sharkey
Zones

Sleamaker &
Browning
Zones

Zone 1

-

-

60-70%

Zone 2

115-138

66 - 79%

70-85%

71-75%

Zone 3

139-159

80 - 91%

85-95%

76-80%

Zone 4

160-164

92 - 94%

95-100%

81-90%

Zone 5

165-174

95 - 100%

100%

91-100%

And what if I didn't have the results from a physiology test? I
think I'd have followed S&B's method over Sharkey's. Sharkey's 148 beats at the high end
of Zone "2" is just too hard for long slow distance - I think S&B has a more
realistic range. At Zone 4, it's probably still better to train less hard (S&B) instead of
doing intervals up to my max heart rate.